Scottish ale, Increase DME or not.
 

I am brewing a partial mash Scottish ale kit from Brewers best, Recipe here. I really don't like that it is only 3.5%ABV and would like to kit that up a notch. The recipe calls for 1 lb of DME. I have some 2.5 lbs of extra DME. Would I gain more ABV without disturbing much else by adding the DME?

Yes, you would increase the abv and the body, both good for a Scottish Ale. You may want to increase the bittering hops to 1 oz to compensate for the additional fermentables, but seeing as the recipe doesn't give the alpha acid, I'd opt for adding the extra 1/2 ounce.

A few things: You'd probably want to ditch that smoked malt. It really doesn't have any place in a Scottish ale, apparently that's just something American brewers attributed to being "Scottish", yet anywhere you read about brewing the style really turns its nose at smoked malt. If you do end up taking it out, try replacing it with something like a dark crystal malt. And adding all of that extra DME you have will push it to the very limit of OG for a Scottish ale, and you'll probably end up with around the ballpark of 5% abv. If you do choose to go that route, just bitter with the full 1 oz they give you in the kit. You'll need the extra IBUs to compensate for the increase in gravity, along with not needing any hop aroma in the finished beer anyways.

I wouldn't completely knock a beer just because it's only 3.5% ABV. I enjoyed my 3.9% Scottish ale so much that I can't wait for my new one.

You could probably add a half pound of DME and use all the hops for bittering and end up with a Scottish 80/-, rather than what right now appears to be a Scottish 60/-. I really wouldn't recommend adding much more than that.

Thanks for the response. I will increase the DME and see if it falls into the 80 schilling category. Also I want to swap the Cascade hops to Fuggle hops, any thoughts on that?

Scottish ales should have very low hop aroma, so changing hops shouldn't matter too much.

Beer turned out great!
 

So I brewed this beer and did switch cascade to fuggles. I really liked the effect the increase DME had. It did not have as watery a mouthfeel as some of the scottish ales have had (i.e. Belhaven Scottish Ale). The point about the scottish ales not having a smokey flavor is spot on. I did use the smoked malt and the taste of it faint but noticeable. However, it does not belong in the style, after having a fair amount of scottish ales, there was a noticeable difference in American made scottish ales using smoked malt over the Scots who had no such flavor. Overall a decent beer and people liked it a lot.